Any number of ComponentKeys can be held in the item keyed on the
ProductNo. Any number of WorkProcesses can be held in the item for each
ComponentKey. Shocking to the purists I suppose, but hey, we want to
get on and get these things made and sold don't we?

Cheers,
Mike.

In article <8n515u$5ge$1_at_news.ncu.edu.tw>,
"ªL¨Î§»" <s8423022_at_cc.ncu.edu.tw> wrote:
>> A `product' is made by it's `component' and a `component' is
made by
> several `work process'.> I think I may need five tables in the database, but is this a
good
> design???>> Tables:>> 1. product(pid,name) primary key(pid)> 2. component(pid,cid) primary key(pid,cid)> foreign key(pid)
reference
> product.pid> foreign key(cid)
reference
> component.cid>> 3. component_item(cid,name) primary key(cid)> 4. work_process(pid,cid,wid,step) primary> key(pid,cid,wid,step)>

foreign
> key(pid,cid) reference component(pid,cid)>

foreign
> key(wid) referenc work_process_item(wid)> 5. work_process_item(wid,name) primary key(wid)>> it seems that there are too many tables and too many identifer
( ex.
> pid, cid, wid...)> and the few fields in each table (for example, component_item,> work_process_item,...).> The requirements are quite simple.> I just want to know what work process are needed to produce a> product,> and what components make up a product, and each steps to make
a
> component.> because the requirements are quite simple, sometimes, I
think that
> maybe there are too many tables.> maybe we could put all the things in one big table? like this> (id, product, component, step, work_process)>> The question are:> 1. is this a good design?> 2. should I use the component' name as it's identifer and
delete
> the cid field from component_item table?> and use work process' name to identifer
work_process_item
> but not wid?> 3. if the answer of questoin 2 is YES,> should I combine work_process_item and component_item
into
> other tables, or one field in one table is good?>> any comment would be appreciated.> thanks a lot.>>